1. Field of the Invention
This invention relates to an integrated process for thermochemically transforming biomass directly into methane. As used herein, the term “biomass” refers to biological material derived from living or deceased organisms and includes lignocellulosic materials, such as wood, aquatic materials, such as algae, aquatic plants, seaweed, and animal by-products and wastes, such as offal, fats, and sewage sludge. In one aspect, this invention relates to a multi-stage hydropyrolysis process for producing methane from biomass.
2. Description of Related Art
Conventional pyrolysis of biomass, typically fast pyrolysis, does not utilize or require H2 or catalysts and produces a dense, acidic, reactive liquid product that contains water, oils, and char formed during the process. High yields of methane may be achieved through conventional fast pyrolysis; however, higher char yields are typically attained through fast pyrolysis in the absence of hydrogen, which decreases methane yield as compared with the method of this invention. Methane may also be produced from biomass by conventional pyrolysis and anaerobic digestion processes. In addition, gasification followed by methanation may be employed for producing methane from biomass.